<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    用户名：<input type="text" id="username"><span></span>
    <script>
        const int = document.getElementById('username');
        const p = document.querySelector('span');
        int.onblur = function() {
            let username = this.value;
            const script = document.createElement('script');
            script.src = 'http://127.0.0.1:8080/username-server'
            document.body.appendChild(script);

        }

        function hendle(data) {
            int.style.border = 'solid 1px red';
            p.innerHTML = data.msg;
        }
    </script>
</body>

</html>